A motor that generates power in, for example, a hybrid vehicle or an electric vehicle is driven with an inverter device. The inverter device includes a plurality of power semiconductor elements that are connected to each other. When the power semiconductor elements have an excessive amount of electric currents due to, for example, an increase of a load applied to a motor, there is a possibility that temperatures of the power semiconductor elements exceed an allowable temperature and lives of the power semiconductor elements are shortened. Therefore, the inverter device has a temperature detection circuit detecting the temperatures of the power semiconductor elements and performs a protecting operation that limits the electric currents based on the detected temperatures.
A temperature detection circuit described in patent literature 1 has diodes located adjacent to power semiconductor elements and detects temperatures of the power semiconductor elements based on forward voltages Vf of the diodes. As well known, the forward voltages Vf of the diodes have negative temperature coefficients.